	uniform mat4 pMatrix;
	uniform mat4 mvMatrix;
	uniform float shell_distance;
	uniform float pass_index;

	attribute vec3 a_position;
	attribute vec3 a_normal;
	attribute vec2 a_texCoord;

	varying vec2  vTexCoord;

	void main(void)
	{
	vTexCoord    = a_texCoord.xy;

	vec4 Position = vec4(a_position,1.0);
	Position.xyz += shell_distance * pass_index * a_normal;
	gl_Position = pMatrix * mvMatrix * Position;
	}